Steam superheater of low-pressure sectional boilers



Patented July 19, 1927. I

PAT E NT OFF ICE.

WALTER n-oursomor mnnnnsnnm'rz, NEAR nnnsnnn, G RM Y.

STEAM SUPERHEATEB OF LOW-PRESSURE SECTIONAL BOILERS.

' Application filed May 12, 1926, Serial No. 108,477, and in Germany May 1924.

My invention. relates to an .llHPlOVBfl steam superheater for use in connection with a low pressure sectional boiler, in which one or several flue gas channels are provided 5 and shaped to form a serpentine path. Boilers of this type usually comprise a plurality of juxtaposed sections made of cast-iron and depending, as regards the number thereof, upon the desired area of the total heating surface.

Generally speaking it is known to superheat the steam discharged from low pressure boilers. The superheaters hitherto ,employed for the purpose, however, are designed to form a compact structure occupying least possible space and which is mounted either over and above the steam generating boiler or in the flues of the latter.

In the former ease the total space the Q0 boiler plant for generating steam of a predetermined tension and superheating temperature requires, is substantially. increased beyond the space required or occupied by the steam generator alone, due to the separate superheater being annexed to surmount the boiler, but in this case the uniform drop of ten'iperature of the flue-gases within the I steam-generating part of the plant remains unaltered or is maintained.

In the latter case very little space only is saved, as compared with the former case, but a plant or structure of this kind is objectionable for the reason that the superheater will act to take off or withdraw from the flue-gases a considerable amount of heat at a certain point of the total length of the path the gases have to travel in and through the steam generator. This is very undesirable .even in wrought-iron boilers, but in a cast-iron boiler it is the more objectionable since the durability of the boiler is seriously endangered and the life of the boiler shortened thereby. In other words, the temperatures of the flue-gases before or in front of and behind or at the rear of the superheater widely differ from each other whilst, on the other hand, the parts of the boiler which are subjected to the action of such differing temperatues, are located close by each other. It will be understood by those to whom this specification is addressed, that conditions of the stated kind are very detrimental and cannot be endured in a castiron boiler.

The object of my invention is to remedy this defect and to provide in a cast-iron boiler of the. stated type having serpentine flue-gas channels a: steam superheating structure which will work in an unobjectionable manner and more economically than hitherto practised in boiler plants of the stated type.

Vith this object in view I provide and mount zig-zag superheater tubes in the fluegas channels so as to follow the zig-zag path thereof and on account of the comparatively great length the single tube necessarily must have it will answer the purpose in most cases to provide preferably two tubes only 111 each zig-zag chamber. preferably shaped to be of sufficient size and capacity without however requiring or occupying any accessive space, and as I prefer to arrange the tubes in accordance with the counter-current principle, as regards the flue-gases on the one hand and the steam to be superheated on the other hand, I real ize a perfect utilization and economy respecting the available heating area afforded by the said tubes, since the hot gases flow in the longitudinal direction of, the tubes and are throughout in contact with the whole peripheral area thereof.

iThe resistance the flue-gases encounter in the zigzag, fines is not noticeably increaser because the few tubes mounted in each'single zig zag flue or chamber of the boiler do not perceptibly reduce the sectional area of the flue or chamber; further a perfectly uniform decrease of the temperature of the gases is insured or maintained in the fines of the boiler.

With the above recited object in view, reference is had to the following specification and drawing in which there is exhibited one example or embodiment of the invention which is in no way intended as a limitation upon the scope of the appended claims as it is to be clearly understood that variations and modifications which properly fall within the scope of said claims, may be resorted to when found expedient.

In the accompanying drawing a boiler with my improved arrangement for superheating steam is illustrated in and by a longitudinal sectional view wherein parts which do not help to disclose the nature of the invention are omitted for clearness sake.

In the drawing the boiler comprises a number of cast-iron sections or members 1 to 10 which when duly assembled, as shown, constitute the grate 11 and the smoke chan- The main flue is nels or Hues l2, l3 and 14 cxtei'iding in a serpentine or zig-zag, configuration as usually in boilers of this type. The steam chambers of the several sections or members communicate with each other and the steam evolved therein is free to rise and flow through the short connecting pipes 15 into the steam collector 16. The steam collecting in the latter is supplied by means of suitable piping equipped with an appropriate valve (not shown), to a distributing chest 17 located in the main flue 18 of the boiler, and from the chest 17 the steam is conveyedt 'ol g a number of tubes 19 to a receiver 20. It will be seen that the tubes 19 are arranged in a serpentine or zig-zag path following the course of the lines M, 13 and 12, that is to say, passing first through the uppermost flue and descending gradually in order to leave the lowermost flue for connection with the said receiver. Further it will be seen that the steam thus flows in counter-current direction to the flow of flue-gases. I

The receiver 20 is likewise arranged in the main flue 18 and the two receptacles 17 and 20 for the reception of hot steam and. superheated steam, respectively may be rigidly interconnected by ribs or flanges 21 or the like, as oesired or required. The superheated steam is discharged from the receiver 21 through an intermediate pipe 22 nto the main steam pipe 23. The valve 2a is provided for the purpose of supplying live steam immediately from the boiler or collector 16, to the superheated steam in the main steam pipe, it required or desired.

I have not attempted to explain all of the minute details of the construction of the boiler, for it will be understood by those skilled in the art, that the parts will be necessarily of the proper size and relationship and will be properly mounted and sup ported according to the tenets of boiler construction. The operation being self-evident it does not seem necessary to burden this specification with an exposition of the advantages which the invention possesscsffor they will be apparent to those versed in the art to which this invention relates.

hat I claim is 1. In a low pressure sectional boiler having a steam collector and zigzag gas pass communicating at one end with the flue and at the other end with the combustion chamber, a steam superheater comprising correspondingly shaped zig-Zag tubes extending longitudinally in the gas pass and connected at their ends adjacent the flue with said steam collector and communicating at their other ends with steam delivery pipe, whereby the flow of steam in said superheater is counter to the flow of heating gases.

2. In a low pressure sectional boiler hav ing a steam collector and a. zig-zag gas pass between the combustion chaiinber and flue, a steam superheater comprising correspondingly shaped zig-zag tubes extending longitudinally in said gas pass, a steam chest connected to said tubes adjacent the exit end of said pass, connections between said chest and said steam collector, a receiver connected with other ends of said tubes, and a main steam pipe communicating with said receiver.

In testimony whereof I have hereunto allixed my signature.

WALTER nonrson. 

